The invention relates to an actuating device with a drive unit that features an electric motor, which motor is arranged in a housing and drives a drive shaft, and with a gear unit that features a drive gear arranged on the drive shaft at least in a rotationally fixed manner, which drive gear in a first gear stage meshes with at least one planetary gear that is embodied as a double toothed gear and is supported on an axle in a fixed position and so that it can pivot, whereby the drive gear drives the larger gear wheel of the double toothed gear, and the smaller gear wheel, which faces the direction of the output side, in a second gear stage meshes with an internally toothed gear or gear segment that is arranged on an output shaft in an at least rotationally fixed manner, so that the output shaft can be driven via the two gear stages.
In DE 100 47 308 A1 a two-stage gear arrangement for an actuating device is described that features a drive shaft on which a drive gear is arranged and that is in operative connection with a two-stage gear on whose output side a centrally arranged output shaft is arranged. In detail, the transfer from the drive gear takes place via three double toothed gears, whose larger gear wheel meshes with the drive gear and whose smaller gear wheel meshes with an internal gear arranged on the output shaft. The entire two-stage gear arrangement is situated in a housing totaling three parts, whereby the first essentially plate-shaped part lying nearest to the drive motor features the bearing of the drive shaft as well as of the axles for the double toothed gears. In a second housing part, the three double toothed gears are arranged in the form of a housing cage whose axles are supported in the housing cage at their second end. In addition this housing cage also features a first bearing point for the output shaft, on which an internal gear is arranged that meshes with the respectively smaller gear wheels of the double toothed gears. This gear unit is essentially tightly closed by a third housing part that is placed on the second part and features a second bearing point for the output shaft.
The disadvantage of such a form of embodiment is the large number of components to be used and assembled, whose sizes must be matched to one another very precisely. This results in increased assembly and production costs, since the respective axles of the double toothed gears, the drive shaft, and the output shaft must be matched to one another very precisely, that is to say a smaller tolerance must be maintained with respect to their parallel position to one another.